Portable rubbing machine assembly



Dec. 25, 1956 J. F. ROODS PORTABLE RUBBING MACHINE ASSEMBLY Filed April 23, 1954 FIG.1

PORTABLE RUBBING MACHINE ASSEMBLY John F. Roods, Burlington, Vt., assignor to Fair-child Camera and Instrument Corporation, a corporation of Delaware Application April 23, 1954, Serial No. 425,171

4 Claims. (Cl. 51-170) This invention relates to portable rubbing machine assemblies and, more particularly, to such assemblies including readily replaceable or interchangeable rubbing platens.

Heretofore there have been proposed various types of portable rubbing machines, the most usual example of which is the portable sanding machine. While suitable for some uses, such machines have failed to achieve certain desirable operating characteristics. For example, it

has been found that for cutting or rapid abrading operation an orbital movement of the rubbing platen is de sirable, while for finishing operations a straightline reciprocating movement is preferable. Such machines of the prior art have been limited to a single type of motion, so that any given machine is best suited for only one type of operation and is a compromise for other operations.

In addition, portable rubbing machines heretofore proposed have left something to be desired as to the facility of replacing the expendable rubbing element, such as sandpaper sheets. Furthermore, many such prior portable rubbing machines have produced excessive vibration at the frame and handle of the device, resulting in excessive fatigue of the operator.

It is an object of the present invention, therefore, to provide a new and improved portable rubbing machine assembly which obviates one or more of the above-mentioned shortcomings of prior machines of this type.

It is another object of this invention to provide a new and improved portable rubbing machine assembly including readily interchangeable rubbing platens adapting the machine for either orbital or straightline reciprocating rubbing movements.

It is another object of the invention to provide a new and improved portable rubbing machine assembly in which the rubbing platen has a full-floating support from the frame and a minimum of vibration reaction at the handle of the machine.

It is a further object of the invention to provide a new and improved portable rubbing machine assembly in which the expendable rubbing element may be replaced with the greatest facility.

In accordance with the invention, there is provided a portable rubbing machine assembly comprising a manually supportable frame and housing including a driving mechanism; a readily disengageable rubbing platen including disengageable supporting connections to the frame,

' a disengageable driving connection to the mechanism, and

releasable clamping means for an expendable rubbing element, and means mounted on the frame and normally free of the platen when engaging the frame but manually operable to engage the clamping means to release the same.

For a better understanding of the present invention, together with other and further objects thereof, reference is had to the following description taken in connection with the accompanying drawing, while its scope will be pointed out in the appended claims.

1 United States Patent Oice 2 ,775,076 Patented Dec. 25, 1956 Referring now to the drawing:

Fig. 1 is a cross-sectional detail view of a portable rubbing machine assembly embodying the present invention;

Fig. 2 is a perspective view of an interchangeable platen unit for use in the apparatus of Fig. 1 and designed for an orbital rubbing movement; while Fig. 3 is a perspective view of an interchangeable platen unit for use in the apparatus of Fig. 1 and designed to have straightline motion.

Referring now to Figs. 1 and 2 of the drawing, there is represented a portable universal rubbing machine assembly comprising a manually supportable frame and housing 10 formed with a unitary handle 11 and including a driving mechanism such as an electric motor (not shown)v having a downwardly extending driving shaft 12. A manually operable switch 13 for the motor is included in the handle 11 and it is understood that a suitable extension cord or equivalent will be connected to the handle 11.

The driving mechanism of the machine also includes a protruding driving element or crank 14 extending from a toothed pully 15 journalled on a stud 16 projecting downwardly from the frame 10 by means of a conventional anti-friction bearing 17. Mounted on the motor shaft 12 is a toothed pulley 18 which is connected to drive the pulley 15 through a cog belt 19. A driving roller 20 is journalled on the crank 14 through anti-friction bearings 21.

The rubbing machine of the invention also is provided with a plurality of resilient stand-off members, such as four cylindrical rubber members 22, at each corner of the frame, which is generally rectangular. Each of the standoff members 22 terminates in a projecting disengageable fastener element 23, preferably in the form of adoubly tapered projecting pin.

The rubbing machine assembly of the invention also includes a readily disengageable rubbing platen, such as the orbital rubbing platen 24 shown in Figs. 1 and 2. This platen includes disengageable supporting connections for securing the platen to the frame and a readily disengageable driving connection to the driving mechanism of the frame. Specifically, the platen includes a plurality of disengageable fastener elements 25, complementary to the fastener elements 23 of the frame, which may be in the form of snap-action receptacles positioned to receive and engage the projecting fastener elements 23. As shown more clearly in Fig. 2, each of the fastener elements 25 is formed by a slotted leaf spring member 26 riveted or otherwise secured to the platen 24. In order to aid in retaining the fastener elements 25 in position during engagement and disengagement, lips 27 are cut out from the platen element 24 and bent over the ends of the elements 25.

The platen 24 also is provided with a member secured thereto and including an element having a slip-fit engagement with the driving element of the frame, specifically, a receptacle 28 for the projecting driving roller 20 of the frame. The receptacle 28 is designed to have a slip-fit engagement with the roller 20 to facilitate engagement and disengagement in contrast to a press-fit or other secured engagements. The receptacle 28 is formed as a unitary part of a plate 29 which is riveted, or otherwise secured, at 30, 30 to the platen 24. In order to minimize the number of different structural elements required for the interchangeable platens, as described hereinafter, the plate 29 includes certain features not used in the case of a platen designed for orbital movement. Since the only connections between the platen 24 and the frame 10 are by means of the snap-action connectors 23, 25 described and the slip-fit driving engagement between the roller 20 and the receptacle 28, it is seen that the platen 24 may be .means for an expendablerubbing element, specifically, a

pan of releasable clamping jawsiill, '31 disposed atopposite ends of the platen, supported therefrom on pivots 31b, 51b, and provided with suitable biasing springs "springs 32, 32for clamping an expendable sheet of rubbing material, such as sandpaper, at opposite ends of the platen. In order that the clamps 31, 31 get a better purchase or grip onther-ub-bingsheet, the ends of the platen are "turned upwardly to form lips 24a, 24a over which the ends of-the rubbing sheet are folded for engagement by the clamps '31, 31. As shown more clearly in Fig.2, the clamps "S'Ihave projecting teeth 31c, While the lips 2 m, 2 6a have projecting. teeth 2%, more firmly to grip the "rubbing sheet. A suitable rubbing block 33 is secured to 'the under-surface of the platen '24.

The rubbingma'chine assembly of the invention also "induces means mounted on the frame '10 and normally free of an engaged platen but manually operable downwardly to engage the clamping jaws 31, '31 to release the same. This releasing means may be in the form of a pair of pu's'hbuttons 34, 34 at opposite ends of the frame and normally biased to a position free of the platen unit 24 by springs 35. When the pushbuttons34, 34 are manually depressed,'they are positioned to engage the tailpieces 31a of the clamping jaws 31 to release the same.

It is believed that the operation of the portable rubbing machine assembly of'the invention'will be apparent from theforegoing'description. 'In brief, the platen 24 is initially assembled with the frame 10 by inserting the roller 20in the'recept'acle 2S, adjustin the position of the crank 14f'un'til the connector receptacles 25 register with the .connectc'r's'23 projecting from the frame and then snapping the platen into engagement with the frame. A sheet of rubbing material, such-as sandpaper, is then placed on a bench or floor and the rubbing machine assembly firmly disposed thereon and pressed downwardly by means of the handle 11. First one and then-the other of the pushbuttons is pressed downwardly, opening. its associated clamping aw-31'so that the sandpaper may be folded over the lip 24a and underthe jaw 31. Upon release of the pushbutto'n 34, the clamping jaw '31 clamps the sandpaper to the platen'24, at the same time exerting a-certain tensto'nbn the paper due to the friction between the-paper and the jaw .31 as it rotates aboutitspivot 31b.

In operation of therubbing machine assembly described, it is seen that the platen 24 has a full floating support from the frame It Its only interconnections are between the resilient stand-oi? members 22 and the slip-fit engagement between the driving roller 20 and the receptacle 28. Therefore, the platen 24 is completely unrestricted-inits direction of motion and will execute an 5 orbitaltmovement which, as statedabovqis most etfective for cutting or rapid abrading operations. In the event that it is desired to operate the machine with a straightline reciprocating motion, as in finishing operations, the platen 24 may-be readily disengaged from the frame it merely by releasing the snap connectors 23, 25 at each corner of the frame and replacing the platen 24 with another platen designedfor straightline reciprocating movement.

Such a straightline reciprocating platen is shown in Fig. 3.. The platen 40 is similar to the platen 24of Fig. 2 except that the receptacle 28 and unitary plate 29 are pivotally supported from the platen 46 by means of a pin 41 on which is journalled a boss or hub 42 formed integrally from the plate 29. The other end of the plate 29 is provided with a U-shaped clip 43 of suitably hardened wearing material, while a bearing surface for the plate 29 during its pivotal movement is provided by a lip 4-4 extending upwardly'and over from the plate 29. In addition, a pair of siderails 45, 45 are secured to each side of the platen 40 and positioned to engage the side members of the frame 10 to restrict the -motion of the platen -40 to straightline reciprocating motion. It will be seen that with this arrangement, the plate 29 and its connected receptacle 28 effectively constitute a connecting rod between the crank roller 20 of the driving mechanism and the platen 40 to impart reciprocating movement thereto. The engagement and the clamping of a suitable rubbing sheet, such as sandpaper, is precisely the same with the straightline reciprocating platen 40 as with the orbital platen 24 described above. It :is seen that the manually operable pushbuttons 34 are normally completely out 'of the .path of any element of the platen assembly, thus vfacilitating ready replacement of platens. They also remain free from the platen elements during their orbital or reciprocating movement in operation of the assembly.

While there has been described what is at present considered to be the preferred embodiment of the invention, it will beobv ious to thoseskilled in the art that various changes and modifications maybe made therein without departing from-the invention, and "it is, therefore, aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

Whatis claimedis:

1. A portable rubbing machineassembly comprising:

a manually supportable frame and housing including a driving mechanism; a readily disengageable rubbing platen including 'disen-gageablesupporting connections to said frame, a disengageable drivingconnection to said1mechanism, and releasable clampingmeans for an expendable rubbingelement; and means mounted on said frame and normally free-of said platen when engaging said frame but manually operable to engage said clamping meansto release the same. p

2. A portable rubbing 'machine assembly comprising: a manually supportable frame and housing including a driving mechanism; a readily 'disengageablerubbing platen including 'disengageable supporting connections to said frame, a disengageable driving connection to said mechanism, and a pair of releasable clamping-jaws at opposite ends of the platen for clamping an expendable sheet of rubbing material; and means mounted on said frame and normally'fre'e of said platen when engaging said frame but manually operable'to engage'said clamping jaws to release the same.

3. A portable rubbing machine assembly comprising: a manually supportable frame and housing including a driving mechanism; a readily di'sengageable rubbing platen including disengageable supporting connections to said frame, a disen-gageable driving connection to said mechanism, and a pair ofreleasable clamping jaws at opposite end of the platen for clamping an expendable sheet of rubbing material; and a pair of pushbuttons mounted on opposite ends of said frame and normally free of said platen when engaging said frame but manua'llymperable 'to engage said clamping jaws to release the same.

4. A portable rubbing machine assembly comprising: a. manually supportable frame and housing including a driving mechanism; a readily disengageable rubbing platen including disengageable supporting connectionsto said frame, a d-isengagea'ble driving connection to said mechanism, and a pair of releasable clamping jaws 'at opposite ends of the platen forclamping-zan expendable sheet of irubbing2material;.and a"pair of spring'biased pushbuttons mountedon oppositeien'ds of said frame and normally free firm engagement with said platen tolfacilitate clamping ofsaid sheet.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS Edstrom Jan. 15, 1935 Lovelace Dec. 30, 1941 5 Crosby Feb. 26, 1946 Osman May 11, 1948 Mandl Dec. 27, 1949 6 Hoy Nov. 14, 1950 Happe Aug. 12, 1952 Robins Oct. 21, 1952 Atkin May 26, 1953 Champayne Feb. 23, 1954 Scace July 13, 1954 Dickinson Dec. 28, 1954 

